Effects of low-dose remifentanil infusion on analgesic or antiemetic requirement during brain function mapping: A retrospective cohort study.

BACKGROUND: Pain and discomfort during the awake phase in awake craniotomy should be relieved to facilitate brain mapping. Although some anaesthesiologists use low-dose (0.01-0.05 µg/kg/min) remifentanil infusion to provide analgesia during this phase, its efficacy and side effects have never been evaluated. Therefore, this study primarily aimed to investigate the effects of low-dose remifentanil infusion on the need for antiemetic treatment during brain mapping and secondarily aimed to determine its effects on the need for additional analgesic treatment. METHODS: This retrospective study included 218 patients who underwent awake craniotomy at our centre from 2008 to 2018. The relationship between low-dose remifentanil infusion during the awake phase and the requirement for analgesic or antiemetic treatment was examined. A multivariable competing risk regression analysis was performed to adjust for patient and operative variables. RESULTS: Sixty-six patients (30.3%) received low-dose (median rate: 0.01 µg/kg/min) remifentanil infusion during the awake phase. Forty-nine patients (22.5%) received an antiemetic and 99 (45.4%) received additional analgesic treatment. The difference in additional analgesic treatment was not significant between patients who received low-dose remifentanil infusion and those who did not (adjusted hazard ratio: 1.13; 95% confidence interval: 0.75-1.70; P = .570); however, the use of antiemetics significantly increased in patients who received remifentanil (adjusted hazard ratio: 1.78; 95% confidence interval: 1.01-3.15; P = .047). CONCLUSION: Low-dose remifentanil infusion during the awake phase in awake craniotomy significantly increased the need for antiemetics but did not decrease the need for additional analgesic treatment.

Derivation and validation of an equation to determine the optimal ventilator setting in children undergoing intracranial revascularization surgery: A single-center retrospective study.

BACKGROUND: It can be difficult to determine the appropriate ventilator settings to maintain normocapnia in children undergoing general anesthesia for surgery for moyamoya disease, especially immediately following anesthesia induction. AIM: We conducted this study to attempt to derive an equation to predict the appropriate ventilator settings and subsequently validated the accuracy of the equation. METHODS: A retrospective study of 91 pediatric patients less than 18 years of age who underwent cerebral revascularization for moyamoya disease at our institution. Fifty-eight patients were used to derive the equation, and the subsequent 33 patients were used to validate the equation. We calculated the required respiratory rate to attain normocapnia based on the median of all values of the minute volume during normocapnia (estimated partial pressure of arterial carbon dioxide of 38-42 mm Hg) and the assumption that the tidal volume was 8 mL/kg body weight. We derived the regression equation from the derivation data set where the required respiratory rate to attain normocapnia was represented by age. We simplified the equation by rounding coefficients to the nearest integer. The level of agreement between the respiratory rate predicted from the equation and the actual required respiratory rate was assessed in the validation group using Bland-Altman analysis. RESULTS: The derived equation is tidal volume = 8 mL/kg body weight, respiratory rate = 24-age/min. Bland-Altman analysis in the validation group revealed that the mean bias between the predicted and actual respiratory rate was 0.29 (standard deviation, 3.67). The percentage of cases where the predicted rate was within ± 10% and ± 20% of the actual rate was 42.4% and 66.7%, respectively. CONCLUSIONS: We derived and validated a simple and easily applicable equation to predict the ventilator settings required to attain normocapnia during general anesthesia in children with moyamoya disease.

Validation of the Radford Nomogram to Estimate the Minute Volume Required to Attain Normocapnia in Patients Undergoing General Anesthesia: A Single-Center Retrospective Study

Objective: The Radford nomogram, an old mathematical chart device to estimate the required ventilation for maintaining normocapnia, remains unvalidated in patients undergoing modern, balanced anesthesia. This study aims to investigate the performance of the Radford nomogram in patients undergoing general anesthesia and derive a simple equation to estimate the minute volume required to attain normocapnia (MVnorm). Methods: This single-center retrospective study enrolled 78 patients (age ≥ 18 years) undergoing cerebral revascularization for Moyamoya disease. We defi ned MVnorm as the median of all values of the minute volume during normocapnia (estimated PaCO2: 38­42 mmHg). We examined the agreement level between the estimated minute volume using the Radford nomogram and MVnorm using the Bland­Altman analysis. Furthermore, we developed and validated a simple equation predicting MVnorm based on gender and a multiple of body weight, using a split-sample validation technique. Results: The Radford nomogram tended to overestimate MVnorm with a mean bias of 560 mL/min (95% limits of agreement, -848­1,968 mL/min). The equation developed using data from the development group (n = 52): required minute volume (mL/min) = 85 × body weight (kg) in male patients and 70 × body weight (kg) in female patients. In the validation group (n = 26), the mean bias of this simple equation was 224 mL/min (95% limits of agreement, -1,264­1,712 mL/min). Conclusion: The Radford nomogram overestimates MVnorm in modern, balanced anesthesia. The simple equation using gender and a multiple of body weight yields similar predictive performance to the Radford nomogram.

Preoperative Hypercapnia as a Predictor of Hypotension During Anesthetic Induction in Lung Transplant Recipients.

OBJECTIVE: To determine the incidence and predisposing factors of hypotension during anesthetic induction in lung transplant recipients. DESIGN: Retrospective study. SETTING: University hospital. PARTICIPANTS: Patients who underwent lung transplantation between 2008 and 2013 (n = 68). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The authors analyzed the mean arterial pressure (MAP) from administration of anesthetic drugs to 10 minutes after endotracheal intubation (ie, the anesthetic induction) among participants who underwent lung transplantation. Patients were considered to have clinically significant hypotension (CSH) when the following criteria were fulfilled: An MAP decrease of>40% from baseline and MAP of<60 mmHg. Overall, 41.2% of patients experienced CSH during the induction of anesthesia. The preoperative partial pressure of carbon dioxide (PaCO2) was significantly higher in patients who experienced CSH during anesthetic induction than in those who did not (p = 0.005). Preoperative PaCO2 predicted the development of CSH during anesthetic induction (area under the curve = 0.702; p = 0.002), with an optimal cut-off point of 55 mmHg determined by maximizing the Youden index. The incidences of CSH during anesthetic induction for patients with (PaCO2 ≥ 55) and without (PaCO2<55) preoperative hypercapnia were 75.0% (95% confidence interval [CI] [53.8-89.2]) and 30.8% (95% CI 26.4-37.3), respectively. After adjustment for known predicting factors, the odds ratio for the relationship between preoperative hypercapnia and CSH during anesthetic induction was 12.54 (95% CI 3.10-66.66). CONCLUSIONS: Hypotension during anesthetic induction is common in lung transplant recipients, and is independently predicted by preoperative hypercapnia.

The clinical course of anesthetic induction in lung transplant recipients with pulmonary complications after hematopoietic stem cell transplantation.

PURPOSE: We examined the clinical course of anesthetic induction in lung transplant recipients with pulmonary complications after hematopoietic stem cell transplantation (post-HSCT), focusing on ventilatory management. We aimed to determine the incidence of oxygen desaturation during anesthetic induction and severe respiratory acidosis after anesthetic induction in post-HSCT lung transplant recipients, and to explore factors associated with their development. METHODS: Nineteen consecutive patients who underwent lung transplantation post-HSCT at Kyoto University Hospital (Japan) were retrospectively studied. Data regarding patient characteristics, preoperative examination, and clinical course during anesthetic induction were analyzed. RESULTS: The incidence of oxygen desaturation (SpO2 < 90 %) during anesthetic induction and severe respiratory acidosis (pH < 7.2) after anesthetic induction were 21.1 and 26.3 %, respectively. Reduced dynamic compliance (Cdyn) during mechanical ventilation was significantly associated with oxygen desaturation during anesthetic induction (p = 0.01), as well as severe respiratory acidosis after anesthetic induction (p = 0.01). The preoperative partial pressure of carbon dioxide in arterial blood (PaCO2; r = -0.743, p = 0.002) and body mass index (BMI; r = 0.61, p = 0.021) significantly correlated with Cdyn, and multivariate analysis revealed that both PaCO2 and BMI were independently associated with Cdyn. CONCLUSIONS: Oxygen desaturation during anesthetic induction and severe respiratory acidosis after anesthetic induction frequently occur in post-HSCT lung transplant recipients. Low Cdyn may, at least partially, explain oxygen desaturation during anesthetic induction and severe respiratory acidosis after anesthetic induction. Moreover, preoperative hypercapnia and low BMI were predictive of low Cdyn.

Microglial activation involved in morphine tolerance is not mediated by toll-like receptor 4.

PURPOSE: Morphine is a powerful analgesic but its effect is often diminished owing to the development of tolerance. It has been suggested that morphine activates microglia through its action on the toll-like receptor 4 (TLR4) in the spinal cord, leading to suppression of the morphine effect. However, it has not been examined whether the development of morphine tolerance is affected by the deletion and mutation of the TLR4 gene. METHODS: Mice were treated with morphine (60 mg/kg) or vehicle once daily for five consecutive days to induce morphine tolerance, which was assessed by the tail-flick test before and after the treatment period. The effect of the microglial inhibitor minocycline, and the effect of TLR4 mutation (C3H/HeJ mouse) and deletion (TLR4-knockout mouse) on the development of morphine tolerance were tested. The expression of the microglial activation marker, CD11b, in the spinal cords of TLR4-knockout and wild-type mice after morphine treatment for 5 days was assessed by reverse-transcription polymerase chain reaction. RESULTS: Minocycline attenuated the development of morphine tolerance in mice. Mutation or deletion of the TLR4 gene did not significantly affect the development of morphine tolerance. CD11b mRNA expression was increased after morphine treatment both in TLR4-knockout and wild-type mice. CONCLUSION: Microglial activation caused by a mechanism independent of TLR4 is involved in the development of morphine tolerance. Further studies are necessary to clarify the cellular mechanisms of morphine-induced microglial activation.

INOH: ontology-based highly structured database of signal transduction pathways.

The Integrating Network Objects with Hierarchies (INOH) database is a highly structured, manually curated database of signal transduction pathways including Mammalia, Xenopus laevis, Drosophila melanogaster, Caenorhabditis elegans and canonical. Since most pathway knowledge resides in scientific articles, the database focuses on curating and encoding textual knowledge into a machine-processable form. We use a hierarchical pathway representation model with a compound graph, and every pathway component in the INOH database is annotated by a set of uniquely developed ontologies. Finally, we developed the Similarity Search using the combination of a compound graph and hierarchical ontologies. The INOH database is to be a good resource for many users who want to analyze a large protein network. INOH ontologies and 73 signal transduction and 29 metabolic pathway diagrams (including over 6155 interactions and 3395 protein entities) are freely available in INOH XML and BioPAX formats. Database URL: http://www.inoh.org/

[Anesthetic management of undiagnosed pheochromocytoma: a case report].

A 55-year-old man was scheduled for resection of an adrenal tumor under the diagnosis of a non-functioning adrenal tumor. He was admitted for unstable angina 58 days preoperatively, and on the second hospital day, he had an episode of ventricular tachycardia for 20 seconds following epigastric pain. Abdominal computed tomography scans revealed a retroperitoneal abscess, which was subsequently drained effectively, and a right adrenal tumor. Because of the almost normal plasma catecholamine concentration, the tumor was considered a nonfunctioning tumor. However, when the surgeon manipulated the tumor during the operation, the patient's blood pressure increased suddenly to 240/120 mmHg. The hypertensive crisis was managed with nicardipine and phentolamine. After resection of the tumor, his blood pressure decreased to 80/40 mmHg, and the patient was treated with ephedrine, phenylephrine, and noradrenaline. After surgery, the tumor was confirmed histopathologically as a pheochromocytoma. The management of patients with a hypertensive crisis under suspicion of pheochromocytoma is discussed.